Liquid chromatograph device

A liquid chromatograph device comprising:

• a first liquid feeding device for feeding a first solution,
• a second liquid feeding device for feeding a second solution,
• a first discharging pipe which is connected to said first liquid feeding device and for discharging said first solution from said first liquid feeding device,
• a second discharging pipe which is connected to said second liquid feeding device and for discharging said second solution from said second liquid feeding device,
• a connection for connecting between said first and second discharging pipes,
• an injector for pouring sample to be analyzed into the solution from said connection and for mixing said sampling with said solution, a column for introducing said solution from said injector and for separating said sample into its constituents,
• a detector for detecting said constituents from said column, and a controller for keeping a total flow rate of said first solution and said second solution at constant and for giving a feed-back gain proportionate to a ratio between the two liquid feeding flow rates.

A liquid chromatograph device comprising:

• a first liquid feeding device for sucking a first solution from a first suction pipe and discharging said first solution to a first discharging pipe,
• a second liquid feeding device for sucking a second solution from a second suction pipe and discharging said second solution to said second solution to a second discharge pipe,
• a third discharge pipe by which said first and second discharge pipes are connected to each other,
• a column into which said first and second solutions are introduced with a sample and for separating the sample into its constituents, and
• a detector for analyzing the constituents,
• wherein said first and second solutions are fed through said third discharge pipe to said column so that a mixing ratio between said first solution and said second solution is being changed in a stepwise manner as time passes by,
• said first liquid feeding device including;
• a first pump and a second pump each being driven by a motor and positioned between said first suction pipe and said first discharge pipe,
• a first sensor for detecting a discharge pressure of said first solution discharged to said first discharge pipe, and
• a first active valve being movable between a first position for connecting said first suction pipe with said first pump and for shutting out said first pump from said second pump and a second position for shutting out said first suction pipe from said first pump and for connecting said first pump with said second pump,
• said second liquid feeding device including;
• a third pump and a fourth pump each being driven by a motor and positioned between said second suction pipe and said second discharge pipe,
• a second sensor for detecting a discharge pressure of said second solution discharged to said second discharge pipe, and
• a second active valve being movable between a first position for connecting said second suction pipe with said third pump and for shutting out said third pump from said fourth pump and a second position for shutting out said second suction pipe from said third pump and for connecting said third pump with said fourth pump,
• wherein said liquid chromatograph device further comprising a controller for giving a feed-back gain proportionate to a ratio between the two liquid feeding flow rates to a signal for controlling liquid feeding flow rates of said first and second liquid feeding devices in order to perform a gradient operation.